Biology subjects

Larsen, M. R.

Publications and source records attributed to Larsen, M. R..

38 records · Page 3Linked to original sources

bioRxiv2019

Simultaneous proteomics and three PTMomics characterization of pro-inflammatory cytokines stimulated INS-1E cells using TiO2 enrichment strategy

Diverse protein post-translational modifications (PTMs) in proteins form complex combinatorial patterns to regulate the protein function and biological processes in a fine-tuning manner. Reversible phosphorylation, cysteines (Cys) modification, and N-linked glycosylation are essentially involved in cellular signaling pathways of pro-inflammatory cytokines, which can induce beta cell death and diabetes. Here we developed a novel mass spectrometry-based proteomic strategy (termed TiCPG) for the simultaneous comprehensive characterization of the proteome and three post-translational modifications (PTMomes) by applying TiO2 enrichment of peptides with reversibly modified Cysteine (rmCys), Phosphorylation, and sialylated N-linked (SAN-) Glycosylation from low amount of sample material with largely minimized sample loss. We applied this TiCPG strategy to quantitatively study the change of the three PTMs in {beta}-cell-like INS-1E cells subject to pro-inflammatory cytokines stimulation. It enabled efficient enrichment and quantitative analysis of 8346 rmCys sites, 10321 phosphosites and 1906 SAN-glycosylation sites from 5853 proteins. Significant regulation was found on 100 proteins at the total protein level, while much higher degree of regulation was identified on 3025 peptides with PTMs from 1490 proteins. The three PTMs were co-regulated in proteins, but demonstrated differential spatial and temporal patterns related to protein cellular localization and function in the time course of cytokines stimulation, and they were extensively involved in essential signaling pathways related to pro-inflammatory cytokine mediated {beta}-cell apoptosis, such as the inducible NO synthase (NOS2) signaling pathway, Overall, the TiCPG strategy is proved as a straight forward and powerful tool for multiple PTMomics studies.

biochemistry↗

bioRxiv2018

Tauopathy in the APPswe/PS1ΔE9 mouse model of familial Alzheimer’s disease

Despite compelling evidence that the accumulation of amyloid-beta (A{beta}) promotes cortical MAPT (tau) aggregation in familial and idiopathic Alzheimers disease (AD), murine models of cerebral amyloidosis are not considered to develop tau-associated pathology. The absence of neurofibrillary lesions in amyloidosis mice remains a challenge for the amyloidocentric paradigm of AD pathogenesis. It has resulted in the generation of transgenic mice harboring mutations in their tau gene, which may be inappropriate for studying a disease with no known TAU mutations, such as AD. Here, we have used APPswe/PS1{Delta}E9 mice to show that tau pathology can develop spontaneously in murine models of familial AD. Tauopathy was abundant around A{beta} deposits, with Gallyas- and thioflavin-S-positive perinuclear inclusions accumulating in the APPswe/PS1{Delta}E9 cortex by 18 months of age. Age-dependent increases in Gallyas signal correlated positively with binding levels of the paired helical filament (PHF) ligand [18F]Flortaucipir, in all brain areas examined. Sarkosyl-insoluble PHFs were visualized by electron microscopy. Tandem mass tag proteomics identified sequences of hyperphosphorylated tau in transgenic mice, along with signs of RNA missplicing, ribosomal dysregulation and disturbed energy metabolism. Human frontal gyrus tissue was used to validate these findings, revealing primarily quantitative differences between the tauopathy observed in AD patient vs. transgenic mouse tissue. Levels of tau mRNA were not different between APPswe/PS1{Delta}E9 and littermate control animals. As physiological levels of endogenous, wild-type tau aggregate secondarily to A{beta} in transgenic mice, this study demonstrates that amyloidosis is both necessary and sufficient to drive tauopathy in experimental models of familial AD.

neuroscience↗